Stomach cancer (also known as gastric cancer or carcinoma of the stomach) is one of the most common cancers, affecting roughly twice as many men as women. More than 8 out of 10 cases are diagnosed in people over the age of 60. The success of treatment depends on how early the diagnosis is made.
Most stomach cancers form a tumor or an ulcer in the inner lining of the stomach. Less commonly, the cancer spreads along the stomach wall without forming a discrete lump. This is known as a diffuse tumor.
There is wide variation from country to country in the numbers of people affected. Less industrialized countries generally have the highest rates. Poorer people in Western countries are also more likely to be affected than the better-off.
The exact causes of stomach cancer are not yet fully understood.
In addition to affecting more men than women, and occurring most in older people (the cancer is uncommon in people under 50) other factors that appear to increase the risk of stomach cancer include:
Early stomach cancer can have very mild symptoms, similar to indigestion symptoms. This includes feeling full after eating only a small meal, heartburn, stomach pain, nausea, vomiting and difficulty swallowing.
As the cancer advances, there may be additional symptoms such as:
If suspected, a doctor should order further investigation. This includes the following:
The process of investigating how far the cancer has spread is known as staging. It is based on how deeply the tumor has invaded the stomach wall, whether or not the nearby lymph glands are affected, and whether the cancer has spread to other organs such as the liver or lungs. The stage a cancer is at helps to determine what treatment is possible and what the likely outcome will be.
If discovered early, stomach cancer can be contained within the stomach lining or stomach wall. However, cancer cells can also invade neighboring organs, and break away and travel to distant parts of the body via the blood stream and lymph channels.
In general, the further that stomach cancer has spread from the original site, the less likely it is that the condition will be cured. This is why recognizing the signs, early diagnosis and treatment are crucial.
It is important to seek medical advice if any symptoms persist despite alterations to lifestyle, such as stopping smoking and eating more healthily, or if they start in someone aged 40 or over.
Gastric cancer is 5 to 10 times more likely in those with chronic atrophic gastritis; the same increased incidence is also found in first-degree relatives of patients with gastric cancer and pernicious anemia.
Helicobacter Pylori infection leads to a significantly increased risk of stomach cancer. About 550,000 new cases of stomach cancer each year are attributable to Helicobacter pylori, the same bacterium that causes ulcers.
October, 2017: A major Chinese study involving 600,000 subjects reported that daily aspirin use results in a 38% reduced risk of developing gastric cancer.
Several previous studies noted a reduction in the risk of esophageal, gastric and biliary cancers among regular aspirin users. A 2012 study showed that those who used aspirin daily had a 40% lower risk of death from stomach cancer. [JNCI J Natl Cancer Inst (2012) 104 (16): pp1208-17]
Nitrates and nitrites, such as those in hot dogs, lunch meats, and other cured meats, increase food levels of nitrates, which can lead to the formation of carcinogenic nitrosamines in the stomach.
Processed meats are often salted or smoked, or nitrites may be added to them, in order to prolong their shelf-life. It may be the case that these treatments increase the risk of developing stomach cancer, but previous studies have given contradictory results.
Said Susanna Larsson, research student at The Institute of Environmental Medicine at Karolinska Institutet in Sweden, "We decided to carry out a meta-analysis. This is an analysis in which we collated all research into processed meats and stomach cancer that we could find".
They found 15 studies, covering 4,704 subjects in the period 1966 to 2006, and the results are unequivocal: the risk of developing stomach cancer increases by between 15% and 38% when consumption of processed meat products increases by 30gm (approximately a half-portion) per day.
["Processed Meat Consumption and Stomach Cancer Risk: A Meta-Analysis"; Susanna C. Larsson, Nicola Orsini and Alicja Wolk; Journal of the National Cancer Institute, Volym 98, Nummer 15, Augusti 2006]
An October, 2001 study by Yale School of Medicine researchers has found that a diet high in cholesterol, animal protein and vitamin B12 is linked to increased risk of a specific type of esophageal and stomach cancer, known as adenocarcinoma of the esophagus and gastric cardia, cases of which increased by 300% between the mid-1970s and 2000.
About 20% of the mortality from stomach cancer is attributable to smoking. There is approximately a 50% increase in the risk of stomach cancer in smokers compared to never-smokers.
Regular and substantial consumption of green tea may provide protective effect against this type of cancer.
Eating a diet rich in fruit and vegetables (which contain antioxidant vitamins) will reduce the risk of stomach problems, including cancer.
Reducing alcohol intake will reduce the risk of stomach cancer.
An October, 2001 study by Yale School of Medicine researchers found that a diet high in cholesterol, animal protein and vitamin B12 is linked to increased risk of a specific type of esophageal and stomach cancer, known as adenocarcinoma of the esophagus and gastric cardia, that has been increasing rapidly. The number of cases increased by 300% between the mid-1970s and 2000, according to lead author Susan Mayne, associate professor in the Department of Epidemiology and Public Health at Yale School of Medicine, and associate director of the Yale Cancer Center.
"We found that many animal-based nutrients found in foods of animal origin are strongly associated with risk of developing these types of cancers and we were able to identify nutrients that presumably would be protective," said Mayne. "We also found that regular users of vitamin C supplements were at significantly lower risk of stomach cancer."
"Our results suggest that prevention strategies for these cancers should emphasize increased consumption of plant foods, decreased consumption of foods of animal origin with the possible exception of dairy products, and control of obesity."
Watch out for cured/smoked foods. Foods such as pickles, ham and bacon should be consumed less. The high rate of stomach cancer in Japan has been traced to the large amount of smoked fish in the Japanese diet. Also, Asians who eat a traditional diet – with lots of salt-cured, pickled and smoked foods – have a high rate of stomach and esophageal cancer. Use herbs and spices to season foods instead.
During analysis of the data from a Yale study (see link between Increased Risk of Stomach Cancer and treatment Vegetarian/Vegan Diet) the research team found that obesity is strongly linked with risk of these cancers. "The increase in the prevalence of obesity in the United States certainly contributes to the time trends... Our results suggest that prevention strategies for these cancers should emphasize increased consumption of plant foods, decreased consumption of foods of animal origin with the possible exception of dairy products, and control of obesity."
Study subjects who ate two or more servings of fish weekly had a much lower risk for esophageal, stomach, colon, rectum, and pancreatic cancers than those who avoided fish. In fact, the rates of these types of cancer were 30 to 50 percent lower among fish eaters. High fish consumption was also associated with lower risks for cancers of the larynx (30 percent lower risk), endometrial cancer (20 percent lower risk), and ovarian cancer (30 percent lower risk).
Researchers at Yale University School of Medicine discovered an increased rate of stomach cancer among those who consumed one or more chili peppers a day, compared to those who did not.
Non-smokers have a significantly lower risk of developing stomach cancer.
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